SEARCH · PubMed Health

Results for “Microinjection”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,099 records · Page 61Linked to original sources

PubMed2005

Impairment of anterograde and retrograde neurofilament transport after anti-kinesin and anti-dynein antibody microinjection in chicken dorsal root ganglia.

The purpose of the present study was to investigate the participation of the motor proteins kinesin and dynein in axonal transport of neurofilaments (NF) in cultured dorsal root ganglia neurons. Therefore, we performed live-recording studies of the green fluorescent protein-tagged neurofilament M (GFP-NF-M) to assay transport processes in neurons. Co-localization studies revealed that GFP-NF-M was capable to build a functional NF network with other NF subunits, including phosphorylated heavy neurofilaments (NF-H-PH). Time-lapse recordings using confocal laser scanning microscopy exhibited fast transport of NF dots in anterograde and retrograde direction through a photobleached gap. Following microinjection of anti-kinesin antibodies or colchicine treatment an impairment of anterograde as well as retrograde NF transport was observed during live-recording experiments. In contrast, microinjection of anti-dynein antibodies only impaired retrograde transport of NF whereas the anterograde movement of GFP-NF-M was unaffected. Treatment of the cells with unspecific antibodies had no effect.

Animals↗

PubMed2001

Microinjection of bombesin into the ventrolateral reticular formation inhibits peripherally stimulated gastric acid secretion through spinal pathways in rats.

Bombesin injected into the cisterna magna potently inhibits gastric acid secretion stimulated by intravenous infusion of pentagastrin. Sites in the medulla oblongata where bombesin acts to suppress gastric acid secretion were investigated in urethane-anesthetized rats with gastric cannula. Bombesin or vehicle was injected into the medullary parenchyma or intracisternally (i.c.) 60 min after the start of an intravenous pentagastrin infusion; gastric acid secretion was monitored every 10 min for 20 min before and 150 min after the start of pentagastrin. Bombesin (0.2, 0.6 or 6.2 pmol) microinjected into the ventrolateral reticular formation (VLRF) inhibited dose-dependently the net acid response to pentagastrin by 40.8+/-11.1, 75.4+/-12.8 and 96.7+/-19.4%, respectively, at the 40-50 min period after microinjection compared with the vehicle group. Bombesin action in the VLRF was long lasting (96% inhibition still observed at 90 min after 6.2 pmol), and completely abolished by cervical spinal cord transection at the C6 level. By contrast, bombesin injected i.c. at 0.2 or 0.6 pmol had no effect while at 6.2 pmol, there was a 79.0+/-3.9% peak inhibition of pentagastrin-stimulated acid secretion. Bombesin (6.2 pmol) injected into the dorsal motor nucleus reduced the acid response to pentagastrin by 29%. The parvicellular and gigantocellular reticular nuclei were not responsive to bombesin. These results indicate that bombesin acts in the VLRF to inhibit pentagastrin-stimulated gastric acid secretion through spinal pathways, suggesting a potential role of medullary VLRF area in the sympathetic control of gastric acid secretion.

Animals↗

PubMed2000

Behavioral effects of intra-nigral microinjections of manganese chloride: interaction with nitric oxide.

1. Microinjection of manganese chloride (MnCl2) into the rat substantia nigra pars compacta (SNc) induces a neurodegenerative process manifested by apomorphine-induced rotational behavior. Manganese intoxication produces a parkinsonism-like phenotype in humans. 2. In addition to motor control the substantia nigra has also been proposed to be related to epilepsy and emotional behavior. 3. Although nitric oxide (NO) participation in neurodegenerative processes is still questioned, neurons stained for NAPDH-diaphorase, a marker of NO-producing cells, are spared in several experimental neuronal lesions. Additionally, NO has also been suggested to participate in motor control. 4. The objective of this study was to analyze the effects of MnCl2-induced nigral degeneration in audiogenic seizure susceptibility, anxiety and motor activity. We also analyzed if NO synthesis inhibition (N(G)-nitro-L-arginine 25 mg/Kg twice a day for 4 days) modifies MnCl2-induced neurodegenerative process. 5. MnCl2 (50 microg) microinjection into the SNc caused a statistical significant higher number of apomorphine (0.75 mg/kg s.c.)-induced rotations. No sensitization to audiogenic seizure was found but the lesion induced an increase of open arm exploration in the elevated plus maze, suggesting an anxiolytic effect. 6. The MnCl2-nigral lesion was accompanied by an increased number of NADPH-d positive neurons in the ipsilateral SNc and striatum (both sides). NO synthesis inhibition potentiated the MnCl2-nigral lesion and reversed the NADPH-d cell number increase. 7. The present results show that MnCl2-nigral lesion can influence emotional behavior and suggest that NO may modify the progression of manganese-induced degenerative process.

Animals↗

PubMed1999

Microinjection of cyclic ADP-ribose triggers a regenerative wave of Ca2+ release and exocytosis of cortical alveoli in medaka eggs.

Medaka (Oryzias latipes) eggs microinjected with the Ca(2+)-mobilising messenger cyclic adenosine diphosphate ribose (cADPR) underwent a wave of exocytosis of cortical alveoli and were thus activated. The number of eggs activated was sharply dependent on the concentration of cADPR in the pipette, the threshold concentration was approximately 60 nM. After injection, a pronounced latency preceded the onset of cortical alveoli exocytosis; this latency was independent of the concentration of cADPR but decreased markedly with increasing temperature. Heat-treated cADPR, which yields the inert non-cyclised product ADP-ribose, was ineffective in activating eggs. When cADPR was injected into aequorin-loaded eggs, a wave of luminescence arose at the site of cADPR injection and then swept out across the egg with a mean velocity of approximately 13 microns/s; the velocity was independent of the concentration of injected cADPR. In such a large cell (diameter of around 1 mm), this is considerably faster than that possible by simple diffusion of cADPR, which unambiguously demonstrates that cADPR must activate a regenerative process. cADPR has been demonstrated to modulate Ca(2+)-induced Ca2+ release (CICR) via ryanodine receptors (RyRs) in many cell types, and consistent with this was the finding that microinjection of the pharmacological RyR modulator, ryanodine, also activated medaka eggs. These results suggest that a cADPR-sensitive Ca2+ release mechanism is present in the medaka egg, that cADPR is the most potent activator of medaka eggs described to date, and that it activates eggs by triggering a wave of CICR from internal stores that in turn stimulates a wave of exocytosis.

Adenosine Diphosphate Ribose↗

PubMed1988

[Microinjection of spermatozoa into the oocyte. An experimental model for assisted conjugation in oligo-asthenozoospermia as a cause of sterility].

This study investigates the possibilities to treat oligo-asthenozoospermia, a cause of sterility, by assisted conjugation. After completing acrosome reaction, normal motile spermatozoa are microinjected into mouse oocytes. After 2 hours of incubation time in medium with lactate and albumins, spermatozoa are put into dibutyryl 3',5'-guanosine monophosphate (dbcGMP) and imidazole for the completion of an acrosome reaction. One motile spermatozoon each was injected microsurgically into the perivitelline space of an oocyte. The survival rate of the oocytes after injection was around 85%. The oocytes with two pronuclei and a second polar body were considered as fertilized. Of those injected oocytes 21.5% were fertilized with acrosome reacted spermatozoa, whereas only 5.6% were fertilized with spermatozoa without dbcGMP treatment. Thus, motile and acrosome reacted spermatozoa essentially fertilize oocytes at microinjection into the perivitelline space very well. This technique may become a hopeful procedure to treat human oligo-asthenozoospermia in an IVF/ET-programme.

Animals↗

PubMed1979

Microinjection of fluorescently labeled alpha-actinin into living fibroblasts.

alpha-Actinin from chicken gizzard labeled with tetramethylrhodamine isothiocyanate has been incorporated into living fibroblast cells by microinjection. Fluorescent labeling of alpha-actinin was carried out such that the conjugated protein was functional in vitro as shown by its ability to bind to F-actin. Within 1-2 hr after injection, diffuse fluorescence was observed throughout the cytoplasm and only faint fluorescence was apparently associated with the stress fibers. During the ensuing 2-15 hr, however, most of the fluorescence was seen as periodicities along the stress fibers and as foci of the microfilament polygonal networks. This distribution of alpha-actinin in the living cells was strikingly similar to that found by indirect immunofluorescence localization of endogenous alpha-actinin in fixed samples of the same cell type. Control studies in which heat-treated (100 degrees C, 2 min) fluorescent alpha-actinin or tetramethylrhodamine isothiocyanate alone was injected into the cells indicated that the stress fiber and polygonal network labeling was specific for "native" fluorescently labeled alpha-actinin. These results suggest that the dynamic properties of proteins and structures in cultured mammalian cells can be studied with the use of microinjection and fluorescence microscopic techniques.

Actinin↗

PubMed1986

Microinjection of partially purified protein factor restores DNA damage specifically in group A of xeroderma pigmentosum cells.

Microinjection of cell extracts prepared from both human placenta and HeLa cells into xeroderma pigmentosum (XP) cells of complementation group A restores unscheduled DNA synthesis (UDS) in these cells after UV irradiation [de Jonge, A., Vermeulen, W., Klein, B. & Hoeijmakers, J. (1983) EMBO J. 2, 637-641]. These cells also showed normal resistance to UV irradiation. The half-life of the factors in the cell extracts corresponding to the UDS activity (factor A) was 14 hr in XP cells of group A, and the maximal level of UDS was exerted 2 hr after microinjection. The factors were sensitive to protease treatment but not to RNase treatment and were found to be approximately equal to 160 and approximately equal to 90 kDa by gel filtration. These two fractions of the factor(s) acted specifically in XP cells of complementation group A among complementation groups A, B, C, D, F, G, and probably E and H.

DNA Repair↗

PubMed1995

Microinjection of mitotic cells with the 3F3/2 anti-phosphoepitope antibody delays the onset of anaphase.

The transition from metaphase to anaphase is regulated by a checkpoint system that prevents chromosome segregation in anaphase until all the chromosomes have aligned at the metaphase plate. We provide evidence indicating that a kinetochore phosphoepitope plays a role in this checkpoint pathway. The 3F3/2 monoclonal antibody recognizes a kinetochore phosphoepitope in mammalian cells that is expressed on chromosomes before their congression to the metaphase plate. Once chromosomes are aligned, expression is lost and cells enter anaphase shortly thereafter. When microinjected into prophase cells, the 3F3/2 antibody caused a concentration-dependent delay in the onset of anaphase. Injected antibody inhibited the normal dephosphorylation of the 3F3/2 phosphoepitope at kinetochores. Microinjection of the antibody eliminated the asymmetric expression of the phosphoepitope normally seen on sister kinetochores of chromosomes during their movement to the metaphase plate. Chromosome movement to the metaphase plate appeared unaffected in cells injected with the antibody suggesting that asymmetric expression of the phosphoepitope on sister kinetochores is not required for chromosome congression to the metaphase plate. In antibody-injected cells, the epitope remained expressed at kinetochores throughout the prolonged metaphase, but had disappeared by the onset of anaphase. When normal cells in metaphase, lacking the epitope at kinetochores, were treated with agents that perturb microtubules, the 3F3/2 phosphoepitope quickly reappeared at kinetochores. Immunoelectron microscopy revealed that the 3F3/2 epitope is concentrated in the middle electronlucent layer of the trilaminar kinetochore structure. We propose that the 3F3/2 kinetochore phosphoepitope is involved in detecting stable kinetochore-microtubule attachment or is a signaling component of the checkpoint pathway regulating the metaphase to anaphase transition.

Anaphase↗

PubMed1980

Restoration of membrane excitability in a behavioral mutant of Paramecium caudatum during conjugation and by microinjection of wild-type cytoplasm.

When cells of the behavioral mutant cnrC of Paramecium caudatum were mated with the wild type, phenotype change from CNR (no backward swinning) to wild type in the cnrC mate occurred immediately after the formation of tight pairs. No change of phenotype occurred when cells of cnrA or cnrB were mated with wild type. Phenotypic change from CNR to wild type in cells of cnrC was also induced by microinjection of wild-type cytoplasm. Microinjection of wild-type cytoplasm induced no change in cells of cnrA or cnrB. Phenotypic change in the cnrC mate during conjugation can be explained by cytoplasmic exchange during conjugation, though transfer of membrane sites for excitability through membrane fluidity cannot be ruled out.

Action Potentials↗

PubMed1954

Bioelectric effects of ions microinjected into the giant axon of Loligo.

1. A technique is described for recording the bioelectric activity of the squid giant axon during and following alteration of the internal axonal composition with respect to ions or other substances. 2. Experimental evidence indicates that the technique as described is capable of measuring changes in local bioelectric activity with an accuracy of 10 to 15 per cent or higher. 3. Alterations of the internal K(+) or Cl(-) concentrations do not cause the change in resting potential expected on the basis of a Donnan mechanism. 4. The general effect of microinjection of K(+) Rb(+), Na(+), Li(+), Ba(++), Ca(++), Mg(++), or Sr(++) is to cause decrease in spike amplitude, followed by propagation block. 5. The resting potential decreases when the amplitude of the spike becomes low and block is incipient. 6. The decrease in resting potential and spike amplitude may be confined to the immediate vicinity of the injection. 7. At block, the resting potential decreases up to 50 per cent, but injection of small quantities of divalent cations may cause much larger localized depolarization. 8. The blocking effectiveness of K(+), Na(+), and Ca(++) expressed as reciprocals of the relative amounts needed to cause block is approximately 1:5:100. Rb(+) has the same low effectiveness as does K(+). Li(+) resembles Na(+). Ba(++) and Mg(++) are approximately as effective as Ca(++). 9. Microinjection of Na(+) may cause marked prolongation of the spike at the injection site as well as decrease in its amplitude. 10. The anions used (Cl(-), HCO(3) (-), NO(3) (-), SO(4) (-), aspartate, and glutamate) do not seem to exert specific effects. 11. A tentative explanation is offered for the insensitivity of the resting potential to changes in the axonal ionic composition. 12. New data are presented on the range of variation, in a large sample, of the magnitude of the resting potential and spike amplitude.

Animals↗

PubMed2002

Reversal of akinesia in experimental parkinsonism by GABA antagonist microinjections in the pedunculopontine nucleus.

Recent studies, mainly in animals, have shown that the pedunculopontine nucleus (PPN) in the upper brainstem has extensive connections with several motor centres in the CNS. This structure has also been implicated in the akinesia seen in patients with Parkinson's disease. Here we demonstrate that microinjection of gamma-aminobutyric acid (GABA) receptor A antagonist substance, bicuculline, into the PPN of non-human primates (n = 2) rendered parkinsonian with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) results in significant improvement of akinesia. The effect of bicuculline microinjection in the PPN matches that of oral administration of L-dopa. This finding opens up new possibilities in the management of akinesia, the most intractable symptom of advanced Parkinson's disease.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

PubMed2004

Pregnancy with frozen-thawed and fresh testicular biopsy after motile and immotile sperm microinjection, using the mechanical touch technique to assess viability.

BACKGROUND: There are few reports of pregnancy using immotile sperm, and none using a purely mechanical assessment of viability. METHODS: In this pilot study, we retrospectively analysed 66 cycles in 61 patients with determinant male factor, recording rates of fertilization, implantation, normal pregnancy and take-home babies achieved with ICSI. Sperm selection was based on morphologically normal appearance under the inverted microscope. Viability of immotile spermatozoa was assessed by the mechanical touch technique to observe tail flexibility and tail shape recovery. RESULTS: Of 17 ICSI cycles using frozen-thawed testicular sperm, six microinjected with immotile and 11 with motile sperm, we achieved fertilization rates of 65.7 and 74.3%, respectively, and five pregnancies (two and three, respectively). Of 49 ICSI cycles using fresh testicular sperm, 10 microinjected with immotile and 39 with motile sperm, we achieved fertilization rates of 73.4 and 64.4%, respectively, and 12 pregnancies (three and nine, respectively). CONCLUSIONS: Immotile (fresh and frozen-thawed) testicular sperm of normal morphological appearance can be used to achieve clinical pregnancy with ICSI. Our results strongly suggest that immotile sperm viability can be assessed by the mechanical touch technique.

Adult↗

PubMed1986

Establishment of two rabbit mammary epithelial cell lines with distinct oncogenic potential and differentiated phenotype after microinjection of transforming genes.

The goal of this work was to establish an assay for transformation of epithelial cells. Two epithelial cell lines were obtained after microinjecting transforming genes into primary rabbit mammary secretory cells. The cell lines were analyzed for their oncogenic potential and for the maintenance of a differentiated phenotype. A fully transformed cell line, which retained epithelial cell organization, was obtained by coinjecting simian virus 40 DNA and the activated human c-Ha-ras gene. The proliferation rate of these cells was high, with a doubling time of 16 h. Their growth was anchorage independent, and they had lost contact inhibition. The cells were tumorigenic in nude mice, but had no metastatic potential. Both microinjected DNAs were efficiently transcribed and translated, in contrast to the casein genes, which were expressed in primary cells but not in the transformed cell line. An immortalized cell line established after injection with simian virus 40 DNA alone was characterized by a moderate rate of proliferation with a doubling time of approximately 30 h. The growth of these cells was contact inhibited and anchorage dependent. The cells were not tumorigenic in nude mice. The viral DNA was expressed during early passages, as shown by the presence of the large T antigen in cell nuclei, but not at later passages. A high number of lactogenic hormone receptors were found associated with the cell surface. Despite the presence of these receptors, no induction of genes coding for milk proteins was observed after addition of prolactin. These data demonstrate that this assay system can be used to assess the immortalizing and transforming potential of candidate oncogenes in epithelial cells.

Animals↗

PubMed1983

Site of action of sleep-inducing muramyl peptide isolated from human urine: microinjection studies in rabbit brains.

1. Sleep-promoting muramyl peptide purified from human urine (SPU) was injected through chronically implanted guide tubes into defined regions of the basal forebrain and brain stem of unanesthetized rabbits. Electroencephalogram (EEG) and body movements were recorded subsequent to each injection. 2. Of 52 injection sites, there were 8 in which microinjection of SPU induced significant increases of slow-wave sleep (SWS) for 5 or more hours. Each active site was tested twice with SPU and once with vehicle control. 3. Seven of the active sites were located in a region extending from the basal forebrain at the level of the optic chiasm to the mesodiencephalic junction. No active sites were found in the lower brain stem. 4. The behavioral and EEG characteristics of the excess SWS induced by microinjection of SPU appeared normal and similar to the excess sleep that follows intraventricular infusions of sleep factor. However, the responses occurred sooner after injections into an active site than after infusion into a lateral ventricle.

Acetylmuramyl-Alanyl-Isoglutamine↗

PubMed1981

[Opiate receptors and sleep. III. Effects of microinjections of DSIP (delta-sleep peptide) in the median thalamus, Periaqueductal gray matter and nucleus of the tractus solitarius of the rabbit (author's transl)].

In the rabbit, microinjections of DSIP (delta-sleep peptide) at optimal doses in the median thalamus, periaqueductal gray matter (22.5 nmol), and nucleus of the tractus solitarius (15.0 nmol) produce slow-wave sleep with abundant recruiting spindles. As is seen with morphine, this effect is blocked by naloxone (160 micrograms intracerebrally; i.c.). At least in the rabbit, DSIP is probably a neurotransmitter or a neuromodulator of the bulbothalamic system inducing slow-wave sleep and particularly recruiting spindles. It is likely to restore slow-wave sleep after supraoptimal awakening i.c. microinjections of morphine.

Animals↗

PubMed1988

Baroreceptor reflex modulation by vasopressin microinjected into the nucleus tractus solitarii of conscious rats.

To determine whether the central vasopressinergic system at the level of nucleus tractus solitarii (NTS) modulates the reflex control of heart rate, we employed a new method for microinjection into the brainstem of conscious, freely moving rats. Baroreceptor reflex function was assessed during pressure changes induced by intravenous administration of phenylephrine (0.25-8 micrograms/kg) and sodium nitroprusside (0.5-16 micrograms/kg) in rats microinjected, through a permanent cannula into the brainstem, with saline, arginine vasopressin (AVP), or an AVP blocker. Baseline levels of pressure and heart rate were not changed by either peptide pretreatment. Restricted injection of AVP (20 ng-0.2 microliter) into the NTS attenuated the reflex bradycardia during pressure increases, with an upward displacement of the baroreceptor reflex function line (p less than 0.01) without change in the sensitivity. Local blockade of endogenous AVP, d(CH2)5Tyr(Me)AVP (1 microgram-0.2 microliter), depressed baroreceptor reflex sensitivity with intense bradycardia to either small or large pressure increases. Baroreceptor reflex control of heart rate in response to decreases in pressure was preserved during pretreatment with AVP, whereas endogenous blockade of AVP increased baroreceptor reflex sensitivity. These effects were specific to the NTS, since in another four rats there were no effects when the injections were made 1 mm above, into the cerebellum. The changes in baroreceptor reflex control of heart rate in conscious, unrestrained rats caused by administration of AVP and its endogenous blockade provide evidence that central vasopressinergic synapses at the NTS are important physiological modulators of baroreceptor reflex function.

Animals↗

PubMed1977

Effect of lesions in the ventral noradrenergic tract produced by microinjection of 6-hydroxydopamine on gonadotropin release in the rat.

Noradrenergic innervation to the hypothalamus is provided principally by the ventral noradrenergic tract (VNAT) which carries the axons of noradrenergic neurons whose cell bodies lie in the brain stem. To determine the importance of the VNAT in the stimulation of LH release induced by progesterone in ovariectomized, estrogen-primed rats, 6-hydroxydopamine (6-OHDA), an agent which selectively destroys catecholaninergic neurons, was microinjected bilaterally into this tract, 2 days after priming of the ovariectomized animals with 5 mug of estradiol benzoate, sc. Following microinjection, 2 mg of progesterone was injected sc to provoke LH release. A surge of FSH and LH release occurred 6 h after progesterone in control animals and those injected with the ascorbic acid diluent into the VNAT. Injections of 6-OHDA into the tract completely blocked both the LHP AND FSH surge. Control injections of 6-OHDA into the superior colliculus, the caudate-putamen or the frontal cortex did not alter the release of FSH and LH induced by progesterone. Twenty-four hours after injection of 6-OHDA into the VNAT, there was a slight reduction in norepinephrine content in the anterior hypothalamic area and a significant reduction in the region of the arcuate nucleus and median eminence. In this experiment, 6-OHDA injections into the VNAT blocked not only the FSH and LH release induced by progesterone but also the increase in serum prolactin which was present in control animals. In normal females, injections of 6-OHDA into the VNAT blocked the proestrous discharge of LH and partially blocked that of FSH. It is concluded that acute interruption of the VNAT induced by a 6-OHDA can block not only the stimulation of FSH and LH induced by progesterone, but also the preovulatory discharge of gonadotropins. The results suggest that increased impulse traffic in the VNAT on the afternoon of proestrus may be involved in induction of the proestrous gonadotropin surge.

Animals↗

PubMed2004

L-proline microinjected into the rat ventrolateral medulla induces a depressor response distinct from L-glutamate.

The neurotransmitter candidate L-proline elicits changes in the cardiovascular system via actions in the brainstem. However, its action have not yet been determined in the ventrolateral medulla (VLM), a brain region critical in mediating vasomotor sympathetic nervous system responses. Microinjections of L-glutamate produce depressor responses in the caudal (C) VLM, but pressor responses in the rostral (R) VLM and the caudal pressor area (CPA) in the far caudal CVLM. The present study tested whether microinjections of l-proline in the VLM produce a pattern of hemodynamic responses distinct from that of l- glutamate. Urethane-anesthetized rats received arterial catheters and were implanted with flow probes around the abdominal aorta (supplies hindquarters). The surface of each rat's VLM was then exposed. L-Proline induced dose- dependent depressor responses in the CVLM (0.003-1.0 M, 34 nl), but did not induce hemodynamic responses in sites of the RVLM (0.01-1.0 M, 34 nl) that responded to L-glutamate (0.01 M, 34 nl). L-Proline injections (0.1 M, 34 nl) induced rapid and consistent depressor responses correlated with coincident decreases in hindquarter resistance (arterial blood pressure/flow) in the CVLM and CPA, but only inconsistent responses in a few sites in the RVLM. In summary, L-proline induced a distinct pattern of depressor responses preferentially in caudal regions of the VLM, and these depressor effects were associated with decreases in hindquarter resistance. These findings indicate that L-proline may have unique roles including cardiovascular regulation independently from L-glutamate, especially in caudal region of the VLM, via a mechanism that involves altering hindquarter resistance.

Animals↗